Author

Kenton Varda <kenton@cloudflare.com> 2025-06-10 22:43:09 -0500

Parents

ac751d6

Tree

0022c00

Add a mechanism by which JS-RPC requests can inject an internal module.

If `JsRpcSessionCustomEventImpl` is constructed with a `wrapperModule` is specified, then it is the name of a builtin internal module. When an RPC is delivered, instead of delivering to the Durable Object directly, the wrapper module is given a chance to wrap the object, and that is called instead. The wrapper module's default export must be a function which takes the DO instance as its parameter and returns a new object to use in its place.

This is intended to allow a privileged caller to call a Durable Object and inject some code to perform introspection on behalf of the owner, without requiring a new version of the app code to be deployed.

For now, there is no way to activate this in workerd itself. This feature will be used by the internal codebase.